1. Technical Field
The present invention relates to a projection image position adjustment method, device, and program for use for a multi-projection display that configures a screen with projection images projected on a projection surface by a plurality of projectors, and the multi-projection display.
2. Related Art
The multi-projection display of a known type subjects projection images from a plurality of projectors to tile projection or stack projection on a projection surface. In such a multi-projection display, the quality of the projection images is dependent on the accuracy of position adjustment applied to the projection images on the projection surface.
With tile projection, for example, when the position adjustment is made with poor accuracy, the projection images are failed to be seamless or the overlay area looks blurred, thereby considerably lowering the quality of the projection images.
To solve such a problem, the position adjustment on the multi-protection display is absolutely needed for the projection images. However, this causes another problem of requiring much time and effort if users manually make such position adjustment, and in this case, such position adjustment requires rich experience in the course.
In consideration thereof, various types of technique of automating the position adjustment have been so far proposed. For example, refer to Patent Document 1 (JP-A-2001-356005), and patent Document 2 (JP-A-2002-365718).
The technique of Patent Document 1 is of measuring the type of position displacement in the following manner. That is, a plurality of test pattern images projected on a projection surface are captured by a camera. The test pattern images each show a brightness distribution of mountain-shaped waveform. From each of a plurality of test patterns in the resulting image capture data, a typical position, i.e., center position of the mountain-shaped waveform, is derived. Based on the resulting typical positions, derived are an interval between the test patterns, and an interval between points of intersection in either the horizontal or vertical direction or in both directions. The points of intersection are those between the line segment connecting the respective test patterns and the adjacent screen. The resulting intervals are used as a basis to measure the type of position displacement.
The technique of Patent Document 2 is of performing position adjustment in the following manner. That is, two adjustment patterns are displayed by two projectors, and their overlay area is displayed with a dark line. The adjustment patterns are each provided with a black display portion along a border portion with its adjacent projection image, and a white display portion inside of the black display portion. The black display portion is reduced in width by degrees, and a camera performs image capture in the course of such width reduction. The resulting image capture data is used to observe the width change of the dark line, and the position at which the dark line is disappeared is stored as a border position. The border position is used as a basis for the position adjustment, i.e., the contours of the projection images from the projectors are adjusted to come at the border position.
The technique of Patent Document 1 may detect any position displacement as long as an image capture device in use is lower in resolution than projection images, but such displacement detection requires complex image analysis. This thus requires an image data processor for use to have high throughput, and even with high throughput, the position adjustment cannot be made at high speed due to heavy calculation load.
The technique of Patent Document 2 has a problem not being able to derive a border position with high accuracy unless using a high-resolution image capture device, i.e., the pixel resolution of a projection image.